diff --git a/test-requirements.txt b/test-requirements.txt
index 669c22e14..5a1499c57 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -9,7 +9,7 @@ mock>=2.0.0 # BSD
 keystoneauth1>=3.3.0 # Apache-2.0
 python-pytun>=2.2.1 # MIT
 python-subunit>=1.0.0 # Apache-2.0/BSD
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 openstackdocstheme>=1.17.0 # Apache-2.0
 os-testr>=1.0.0 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0